1. Field of the Invention
The present invention relates generally to light guides for transferring illuminating light from a light source to surgical instrumentation, and, more particularly, to a flexible liquid light guide for transmitting light in the visible spectral range to an endoscope.
2. Description of the Prior Art
In endoscopic surgical procedures, illuminating light is typically transmitted from an external light source to an endoscope where the light is then transmitted via an illuminating system incorporated within the endoscope to the body cavity to be viewed. A conventional light cable for providing the endoscope with illumination is a fiber optic light bundle having a plurality of optical fibers of glass or optical plastic. The fiber optic bundle is connected at one end to the light source and at the other end to an inlet port of the endoscope. This system is typically referred to as a fiber optic light guide.
A significant drawback of fiber optic light guides concerns their degradation when used over a period of time. Such degradation is due in part to the repetitive flexing the light guide undergoes when the bundle is initially connected to the light source and the endoscope, and during maneuvering about the operative site in the course of the surgical procedure. Since fiber optic light guides are relatively expensive and are intended to be reused, the light guides are typically employed in many surgical procedures over a substantial period of time. Consequently, the light transferring quality of the fiber optic light guide tends to gradually degrade to a point where the level of light emitted by the fiber optic bundle is substantially less than the light initially received from the light source.
One attempted solution to this problem has been to substitute liquids for fiber optic bundles. Examples of such liquid light guides are described in U.S. Pat. Nos. 3,740,113; 3,920,980; 3,995,934; 4,045,119; 4,907,133 and 5,165,773. However, these liquid light guides are subject to their own drawbacks and limitations. In particular, the liquids described and suggested in these patents provide an inferior degree of visible light transmission when compared with convention fiber optic light guides. In addition, many of the liquids described are not biocompatible and are not favored for use in a surgical apparatus. Further, the construction of such known light guides entails significant expense thereby precluding disposal of the light guides after a single use. Consequently, as in conventional fiber optic light guides, these liquid light guides must also be sterilized after each application, thus adding additional expense to the user.
The present invention is directed to a low cost liquid light guide for efficiently supplying an endoscope with illuminating light particularly in the visible spectral range and which may be disposed of after a single use.